Mulloy James C, Cammenga Jörg, MacKenzie Karen L, Berguido Francisco J, Moore Malcolm A S, Nimer Stephen D
Laboratory of Molecular Hematopoiesis, Sloan-Kettering Institute, New York, NY, USA.
Blood. 2002 Jan 1;99(1):15-23. doi: 10.1182/blood.v99.1.15.
The acute myelogenous leukemia-1 (AML1)-ETO fusion protein is generated by the t(8;21), which is found in 40% of AMLs of the French-American-British M2 subtype. AML1-ETO interferes with the function of the AML1 (RUNX1, CBFA2) transcription factor in a dominant-negative fashion and represses transcription by binding its consensus DNA-binding site and via protein-protein interactions with other transcription factors. AML1 activity is critical for the development of definitive hematopoiesis, and haploinsufficiency of AML1 has been linked to a propensity to develop AML. Murine experiments suggest that AML1-ETO expression may not be sufficient for leukemogenesis; however, like the BCR-ABL isoforms, the cellular background in which these fusion proteins are expressed may be critical to the phenotype observed. Retroviral gene transfer was used to examine the effect of AML1-ETO on the in vitro behavior of human hematopoietic stem and progenitor cells. Following transduction of CD34(+) cells, stem and progenitor cells were quantified in clonogenic assays, cytokine-driven expansion cultures, and long-term stromal cocultures. Expression of AML1-ETO inhibited colony formation by committed progenitors, but enhanced the growth of stem cells (cobblestone area-forming cells), resulting in a profound survival advantage of transduced over nontransduced cells. AML1-ETO-expressing cells retained progenitor activity and continued to express CD34 throughout the 5-week long-term culture. Thus, AML1-ETO enhances the self-renewal of pluripotent stem cells, the physiological target of many acute myeloid leukemias.
急性髓系白血病1（AML1）-ETO融合蛋白由t(8;21)产生，在40%的法美英M2亚型急性髓系白血病中可检测到。AML1-ETO以显性负性方式干扰AML1（RUNX1，CBFA2）转录因子的功能，并通过结合其共有DNA结合位点以及与其他转录因子的蛋白质-蛋白质相互作用来抑制转录。AML1活性对于确定性造血的发育至关重要，AML1单倍体不足与发生急性髓系白血病的倾向有关。小鼠实验表明，AML1-ETO的表达可能不足以引发白血病；然而，与BCR-ABL亚型一样，这些融合蛋白所表达的细胞背景可能对所观察到的表型至关重要。利用逆转录病毒基因转移来检测AML1-ETO对人造血干细胞和祖细胞体外行为的影响。在转导CD34(+)细胞后，在克隆形成试验、细胞因子驱动的扩增培养和长期基质共培养中对干细胞和祖细胞进行定量分析。AML1-ETO的表达抑制了定向祖细胞的集落形成，但增强了干细胞（鹅卵石区形成细胞）的生长，导致转导细胞相对于未转导细胞具有显著的生存优势。表达AML1-ETO的细胞在长达5周的长期培养中保留了祖细胞活性并持续表达CD34。因此，AML1-ETO增强了多能干细胞的自我更新能力，而多能干细胞是许多急性髓系白血病的生理靶点。
